Try lowering the PH a tad. I have been reading up one them because I wanted to try them out. From what I have gathered they like the 7.6-7.8 range. TDS might be a little high for them too because they seem to be delicate. I am not sure about the temperature, I know they like it hot but around 78 degrees is what I have been hearing.

Sometimes you might be feeding too much. There are microorganisms in an establish tanked that can support babies.